class Solution {
public:
    bool CheckPermutation(string s1, string s2) {
        if(s1.size()!=s2.size())return false;
        int hash[26]={0};
        for(auto ch:s1)hash[ch-'a']++;
        for(auto ch:s2)
        {
            hash[ch-'a']--;
            if(hash[ch-'a']<0)return false;
        }
        return true;

    }
};
